M.C.
you should aslo do some pricing. sounds like a cute idea but anyone can serve a taco bar at a party. you'd have to find a niche. mini tacos, unique combinations, etc.
you should also price out supplies - shells, tortillas, lettuce, tomatoes, sauces, toppings, warmers, transport dishes, etc. you'll need a price point so that you can decide on what to offer, price, etc.
M.